There are two different classes. star clusters which can be easily distinguished from each other. Open star clusters are relatively sparsely populated and mostly populated by young stars. But, globular clusters as a rule, highly populated and may contain hundreds of thousands of very old stars. globular cluster, Messier 15, orbits around the center of our Milky Way Galaxy and contains a large population of very elderly stars. In November 2013, astronomers studying this fascinating cluster discovered that he has hidden secrets - in the heart there is something mysterious and dark, hiding in ominous silence!
Astronomers believe that our own Star, the Sun, was born long ago in open cluster inhabited by his long lost fiery sister stars. In fact, almost all stars are born in groups. Most stars, such as our own Sun in its infancy, are formed in favorable conditions that are relatively peaceful - small clusters which quickly fall apart, and their individual members go in their own stellar ways. Others, alas, are doomed to inhabit the older, dense clusters where sister-stars collide with each other and push each other over the precious space - while stormy stellar winds and powerful radiation erupt through the space between the stars, they separate planetary material from sisters-stars.
Globular Clusters so named because their constituent stars are tightly packed in a symmetrical, almost spherical shape. These spherical clusters are the largest and most massive of all star clusters. Several globular clusters in our Milky Way are visible to the naked eye as blurred patches of light, but they received sufficient attention only after the telescope was invented. First recording globular cluster located in the constellation Sagittarius , dates back to 1665 - and it was extremely named Messier 22 , or M22. Second globular was spotted by the English astronomer and mathematician Edmond Halley in 1677. Research globulars proved valuable because they greatly helped astronomers in understanding our Milky Way Galaxy. In 1917, as a result of observations of the distributions and the differences of globular clusters American astronomer Harlow Chapley, then Mount Wilson Observatory in California, was able to determine that the center of the Milky Way is located in Sagittarius region.
Messier 15 --or M15 For short, it was discovered in 1746 by Jean-Dominic Maraldi, and it was included in the detailed comic book catalog of Charles Messier in 1764.
M15 about 33,600 light years from our solar system, and it is about 175 light years in diameter. At about 12 billion years old, it certainly is one of the oldest globular clusters bouncing around in our galaxy. With a total brightness of about 360,000 times greater than that of our Sun, M15 easy one of the most tightly packed globular clusters in our Milky Way. His heart - or core - experienced core collapse , which is a form of compression, and it has a central density, which is inhabited by a huge number of brilliant stars that surround it.
This wonderful, mysterious, star bauble in the sky is home to more than 100,000 fiery stars, and is also notable for covering about 112 variable stars (a large number for this class of stars), and pulsars including one double neutron star system.
NASA / ESA Hubble Space Telescope (HST) managed to capture the best image M15 by showing that this sparkling object can also hide a rare black hole in its hidden heart!
Despite the name, the black hole is not empty. Instead, such an object is a large amount of a substance compressed into a very small area. Imagine a star of ten or more star masses packed in a ball that is about the same diameter as Boston. The result is such a powerful gravitational field that nothing , not even light, can escape from this mighty gravitational capture! For many, these strange objects are the most exciting objects in space.
Although the name “black hole” did not exist until 1967, when the late visionary doctor Dr. John Wheeler of Princeton University and the University of Texas at Austin came up with this idea - this concept has indeed existed for many centuries. Black holes were predicted by Albert Einstein Theory of General Relativity which demonstrated that when a heavy star dies, it leaves behind a weak, tiny relic core. If the mass of the nucleus is greater than about three solar masses, the Einstein equations showed that gravity overloads all other forces, and a black hole is born!
Most black holes are born from the remnants of a massive star that perished in a supernova firework. If the total mass of the star is large enough, it is theoretically possible to demonstrate that there is no force that can hold the doomed massive star from falling under the action of gravity. However, when the ill-starred star collapses, strange things happen. As the star's surface approaches an imaginary surface, called event horizon The time on the star slows down relative to the time left by the observers away. When the surface reaches event horizon , time stands still - and the doomed star may not move further, because it has become frozen collapsing object.
Even large black holes can occur due to stellar collisions. Although the basic formation process is understood, one grumbling secret remains - black holes, apparently, exist on two very different size scales. At the smaller end, the Universe appears to be covered with countless black holes of stellar mass — the relics of massive stars who died in the fire explosions of supernovae. , Black holes "stellar mass" usually range from 10 to 24 solar masses. At the larger end are “supermassive” black holes that lurk in the hearts of probably every large galaxy in the universe.
Historically, most astronomers have long thought that neither the average size, intermediate black holes pursue cosmos. However, recent data from X-ray telescope Chandra, XMM-Newton, and Hst suggests that intermediate black holes do exist. One hypothetical mechanism for the birth of supermassive black holes is associated with a chain reaction of violent collisions between sister stars in compact star clusters which leads to the growth of extremely massive stars. These extremely massive stars then collapse to form medium massive black holes. star clusters then dive into the center of the galaxy where excellent medium massive black holes merge to cause a supermassive black hole!
Hidden secrets in the dark!
Messier 15 - a brilliant, multi-colored display of stellar fireworks. Hot blue stars and colder golden stars swarm together like bees in a pool of sticky syrup in Hst form. Blue and gold stars have become more focused towards ball & # 39; s bright, secretive center. M15 definitely one of the most globulars , has most of its heavy mass, concentrated in the center.
But this star jewel in the sky has kept some secrets. Astronomers watching it spherical, with respectable Hst , discovered back in 2002, that there is something mysterious and dark in his heart. Two favorable theories suggest that this mysterious entity can be either a collection of dark neutron stars, or black hole medium weight! Of the two sentences, the more likely it is that M15 It has medium massive black hole in the heart, like another massive globular, Mayall II.
Astronomers believe that medium massive black holes are formed either by the merging of some small black holes of a black star, or as a result of the collision of massive stars living in crowded, dense clusters. The third sentence suggests that medium massive black holes were born during the swelling of the Big Bang of the Universe almost 14 billion years ago. As for the mass, intermediate black holes remain between the more frequent black holes of a black hole and supermassive black holes - and therefore they can tell astronomers how black holes evolve and grow in clusters such as M15, and inside the galaxies. Our own Milky Way carries a supermassive black hole. It is called Sagittarius A * , or Sag A * (pronounced saj-a-star) and it weighs millions of suns.
In addition to medium massive black hole M15 conducts planetary nebula, Pease I - and this was the first globular known to harbor one of these beautiful objects. Planetary , sometimes called the "butterflies" of Cosmos by astronomers who are fascinated by their great beauty, are formed when a sun-like star emanates from nuclear fuel and "dies" - its outer, multi-colored gaseous layers inhale into the space between the stars. The dying star is doomed to death, leaving only its relic core, called white gnome This star relic is surrounded by beautiful Planetary!
New image M15 courtesy of Hst was produced it Wide field camera 3 and Extended camera for polls in the ultraviolet, infrared and optical parts of the spectrum.
